The present invention relates to a method of assembling aircraft systems and, more particularly, relates to a method of assembling aircraft wings, stabilizers, or other major aircraft systems.
Conventional manufacturing techniques for assembling components and subassemblies to produce airplane wings to a specified contour rely on fixtured xe2x80x9chardpointxe2x80x9d tooling techniques utilizing floor assembly jigs and templates to locate and temporarily fasten detailed structural parts together to locate the parts correctly relative to one another. This traditional tooling concept usually requires primary assembly tools for each subassembly produced, and two large wing major assembly tools (left and right) for final assembly of the subassemblies into a completed wing.
The assembly tooling is intended to accurately reflect the original engineering design of the product, but there are many steps between the original design of the product and the final manufacture of the tool, so it is not unusual that the tool as finally manufactured produces missized wings or wing components that would be outside of the dimensional tolerances of the original wing or wing component design unless extensive, time consuming and costly hand work is applied to correct the tooling-induced errors. More seriously, a tool that was originally built within tolerance can distort out of tolerance from the hard use it typically receives in the factory. Moreover, dimensional variations caused by temperature changes in the factory can produce a variation in the final part dimensions as produced on the tool, particularly when a large difference in the coefficient of thermal expansion exists between the tooling material and the wing material, as in the usual case where the tooling is made of steel and the wing components are made of aluminum or titanium. Since dimensions in airplane construction are often controlled to within 0.005xe2x80x3, temperature induced dimensional variations can be significant.
Wing major tooling is expensive to build and maintain within tolerance, and requires a long lead-time to design and build. The enormous cost and long lead-time to build wing major tooling is a profound deterrent to redesigning the wing of an existing model airplane, even when new developments in aerodynamics are made, because the new design would necessitate rebuilding all the wing major tools and some or all of the wing component tooling.
The capability of quickly designing and building custom wings for airline customers having particular requirements not met by existing airplane models would give an airframe manufacturer an enormous competitive advantage. Currently, that capability does not exist because the cost of the dedicated wing major tooling and the factory floor space that such tooling would require are prohibitively expensive. However, if the same tooling that is used to make the standard wing for a particular model could be quickly and easily converted to building a custom wing meeting the particular requirements of a customer, and then converted back to the standard model or another custom wing design, airplanes could be offered to customers with wings optimized specifically to meet their specific requirements. The only incremental cost of the new wing would be the engineering and possibly some modest machining of headers and other low cost tooling that would be unique to that wing design.
The disadvantages of manufacturing processes using hard tooling are inherent. Although these disadvantages can be minimized by rigorous quality control techniques, they will always be present to some extent in the manufacture of large mechanical structures using hard tooling. A determinant assembly process has been developed and is in production for airplane fuselage manufacture, replacing hardpoint tooling with self-locating detail parts that determine the configuration of the assembly by their own dimensions and certain coordinating features incorporated into the design of the parts. This new process, shown in U.S. Pat. No. 5,560,102 entitled xe2x80x9cPanel and Fuselage Assemblyxe2x80x9d by Micale and Strand, has proven to produce far more accurate assemblies with much less rework. Application of the determinant assembly process in airplane wing manufacture should yield a better process that eliminates or minimizes the use of hard tooling while increasing both the production capacity of the factory and increasing the quality of the product by reducing part variability while reducing the costs of production and providing flexibility in making fast design changes available to its customers. These improvements would be a great boon to airframe manufacturers and its customers and would improve the manufacturer""s competitive position in the marketplace. The present invention is a significant step toward such a process.
According to the principles of the present invention, an advantageous method of assembling an aircraft wing is provided. The method employs modular vehicles in an autonomous, ground-based transportation system to reduce cycle time. These vehicles operate synchronously relative to each other and increase flexibility and reduce the amount of necessary floor space. Variation between parts and the associated costs of assembly are reduced through this method of progressive assembling the aircraft wing through a number of assembly stations using single piece flow and determinant assembly for part to part indexing. Additionally, the present invention provides a method of horizontally building an aircraft wing, which eliminates the high costs associated with scaffolding, tools, and fall protection associated with conventional build methods.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.